Vaporization and Combustion of Single Liquid Fuel Droplets in a Turbulent Environment

Hydrocarbon Droplet Turbulent Combustion in an Elevated Pressure Environment

“…They reported that the droplet burning rate increases linearly with the free airstream velocity when the droplet is enveloped by the flame, and decreases sharply to below the stagnant case burning rate when a wake flame sits downstream of the droplet. It is interesting to notice that the present results, which showed that the burning rate at atmospheric pressure is insensitive to turbulence before extinction, are in agreement with those of Ohta et al [12] within a comparable turbulence range (turbulence intensity between 0 and 0.40 m/s). However, Ohta et al [12] showed a linear increase in the burning rate when turbulence intensity is greater than about 0.40 m/s but less than 1 m/s, whereas the present experiments at atmospheric pressure showed flame extinction when turbulence intensity is greater than 0.40 cm/s.…”

“…It is interesting to notice that the present results, which showed that the burning rate at atmospheric pressure is insensitive to turbulence before extinction, are in agreement with those of Ohta et al [12] within a comparable turbulence range (turbulence intensity between 0 and 0.40 m/s). However, Ohta et al [12] showed a linear increase in the burning rate when turbulence intensity is greater than about 0.40 m/s but less than 1 m/s, whereas the present experiments at atmospheric pressure showed flame extinction when turbulence intensity is greater than 0.40 cm/s. Droplet size (where the porous sphere of Ohta et al [12] is at least 3 times greater than the present droplet; and also fuel was continuously/steadily injected into the porous sphere/droplet) has a significant role in that larger size droplets produce greater vapor rate [27], which makes it possible to maintain the fuel-air mixture at the flame zone within its flammability limits.…”

“…It is also surprizing that the burning rate, at high turbulence levels before reaching flame extinction, drops to below its counterpart in stagnant atmosphere (no turbulence) at the same ambient pressure. This trend is in agreement with the findings of Ohta et al [12] who used a porous sphere (with n-hexane as the fuel) having a diameter of 3 mm, and larger, exposed to a turbulent field at atmospheric pressure. Similar scenario has also been reported by Huang and Chen [27] who examined numerically the burning of (1.3 mm in diameter) n-heptane droplet exposed to a free airstream having a mean velocity in the range between 0.199 to 1.320 m/s at room conditions.…”

“…Their findings revealed that prior to flame extinction, the variation of the turbulent kinetic energy did not show an effect on the droplet burning rate compared with the stagnant case. Their findings were not in agreement with those of Ohta et al [12] who employed a large porous sphere and found an increase in the burning rate with turbulence at atmospheric conditions. Mitsuya et al [13] investigated the interaction between the flame of a suspended droplet and a vortex tube at atmospheric and elevated pressure conditions under both normal and microgravity conditions.…”

“…The effect of forced flow/convection on hydrocarbon droplet combustion has been studied quite extensively under laminar flow conditions and therefore there is a wealth of knowledge (see, e.g., recent references [1][2][3][4][5][6][7][8][9][10], and references cited therein, M. Birouk ( ) · S. L. Toth Department of Mechanical Engineering, University of Manitoba, Winnipeg, MB R3T 5V6, Canada e-mail: madjid.birouk@umanitoba.ca to cite only a few). However, studies reporting on the effect of a turbulent or an acoustic field are quite limited (e.g., [11][12][13][14][15][16][17]). Birouk et al [11] investigated experimentally the combustion of a suspended hydrocarbon droplet under turbulent flow environment at atmospheric/room conditions.…”